Mechanical characteristics of tungsten-containing carbon nanosprings grown by FIB-CVD

Tungsten-containing carbon (WC) nanosprings fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) using a source gas mixture of phenanthrene (C"1"4H"1"0) and tungsten hexacarbonyl (W(CO)"6) showed unique characteristics they could expand and contract as flexibly as macro-scale springs. The large micro-scale displacements of the WC nanosprings were measured through optical microscope observation. In addition, we found that the spring constants of the springs rose as the W content increased. Moreover, the WC springs with a W content higher than 3% had an estimated Young's modulus of more than 200GPa; this value exceeds Young's modulus of diamond-like carbon springs grown by FIB-CVD and is feasible for nanoelectromechanical applications.